Ruby For Programmers of Other Languages: Variables

Variables in Ruby, like variables in PHP, don’t have to be given a type when they are declared, but they do have to be given a value before they are used, let’s make a variable that holds a string and display its value.

Giving Values to Variables:

variable="word"
puts variable

Variables can be assigned different types at any time. For example we can change the value of a variable from a string to an integer, double or float.

# make string variable
variable="word"
puts variable
# change to integer variable
variable=3
puts variable

The result of this code will be

word
3

Like with other languages you can also assign a variable to another variable.

# make string variable
variable='word'
puts variable
# assign an integer
variable=3
puts variable
# assign a variable to another variable
anotherVariable=variable
puts anotherVariable

Naming Variables:

Variable names cannot begin with number or symbols except for the underscore “_”

#example
_variableName="value"

Constants:

As you know, constants are variables whose value cannot change. All you need to do make a constant is begin a variable name with an uppercase letter.

#example
Constant="value"

A constant’s value can change on a different scope, we’ll talk more about how this works when we get to OOP.

Global Variables:

These are variables that are available anywhere in your program. To specify a global variable put a the “$” sign in front of the name.

#example
$globalVariable="value"

Instance and Class Variables:

Instance variable begin with the @ sign, class variables begin with two @ signs

# instance variable
@instanceVar
# class variable @@classVar

We will cover these two last types of variables when we talk about classes, for now just remember how they are declared.